In August 2004, Michael Oher was living with Sean and Leigh Anne Tuohy and their two children in Memphis. Oher, who had bounced around several foster homes, was a top prospect to play major college football and seemed headed to the N.F.L. when the Tuohys took him in.

But there were complications. Because the Tuohys were not Oher’s parents, providing support to him could have been seen as breaking N.C.A.A. rules against providing benefits to recruits. As significant donors to the University of Mississippi, one of the colleges recruiting Oher, the Tuohys might subject themselves and the school to penalties in case of a violation.

So they put together a plan. They asked a court to give them wide authority over Oher’s affairs, including power of attorney, control of his medical decisions and the right to approve financial contracts on his behalf. The arrangement, they believed, would satisfy the N.C.A.A. Oher, then 18 and legally an adult, agreed to it.

Everyone who has seen the 2009 film “The Blind Side” knows what happened next: Oher attended Mississippi, the Tuohys’ alma mater, and went on to the N.F.L. Sandra Bullock won an Academy Award for her portrayal of Leigh Anne Tuohy despite criticism that the film perpetuated tropes about Black athletes like Oher lacking intelligence and needing help from white people like the Tuohys.

Now the legal relationship, known as a conservatorship, and the Tuohys’ motives are under scrutiny. Oher, 37, has filed a petition asking that the nearly 20-year conservatorship be ended. He alleges that the Tuohys used it to profit from his story, including through the movie deal, in ways he didn’t know about.

The Tuohys, who made millions in the restaurant business, have agreed to end the conservatorship, but have denied cheating Oher and in a statement called his petition a “shakedown.”

This much is clear: The conservatorship departed in several ways from Tennessee legal norms. According to the case file, a court granted the Tuohys’ petition even though Oher didn’t meet the criteria for a person needing a conservator. Nor, as typically required, did the court compel the Tuohys to disclose how they handled Oher’s affairs, even though he had the potential to sign a lucrative N.F.L. contract.

The unusual arrangement — and the workaround the Tuohys devised to help Oher qualify academically to play in college — reflect the football-mad culture of the University of Mississippi, the Tuohys’ deep connections to the university and the football program, and the lengths they went to stay within N.C.A.A. rules.

“The whole thing is just bizarre,” Susan Mee, a lawyer in Tennessee who focuses on conservatorships, said of the legal arrangement, adding that the Tuohys should have updated the court when Oher became a millionaire pro athlete.

The Tuohys and their lawyers declined interview requests from The New York Times, as did Oher and his lawyers.

Many people are familiar with conservatorships because of the story of Britney Spears, whose affairs were controlled under such an arrangement in California for nearly 14 years.

To arrange the conservatorship of Oher, the Tuohys turned to Debbie Branan, a lawyer and family friend who, like Leigh Anne, had been a member of the Kappa Delta sorority at Mississippi. She was later the treasurer for their foundation, and her daughter, Whitney, was credited with a minor role in “The Blind Side” movie.

Branan, whose legal practice includes family law matters and commercial real estate deals, represented the Tuohys in the conservatorship. Oher didn’t have independent representation. Branan did not respond to requests for an interview.

Under Tennessee law, courts set up conservatorships to protect a person “with a disability who lacks capacity to make decisions in one or more important areas.” Conservators are often relatives or caretakers.

“The judge has to find a disability or incapacity that renders them unable to make decisions for themselves,” said Amy Bryant, director of conservatorship management for Davidson County, which includes Nashville.

But the Tuohys never said Oher was disabled and couldn’t make his own decisions. Indeed, their petition stated that he had been examined by a physician and had “no known physical or psychological disabilities.” They didn’t specify a reason for the conservatorship, only that Oher had no assets and wanted to live with them, and that they had the means to take care of him.

Oher and the Tuohys had “enjoyed a close and familial relationship for many years,” the petition said.

In his December 2004 order granting the arrangement, Judge Robert Benham reiterated that Oher seemed physically and mentally fine, a finding that did not meet the common legal standard for a person needing a conservator.

Several other typical steps were also skipped, including the appointment of an investigator who would have assessed Oher’s need for a conservator and considered whether the Tuohys should serve in that role. Nor did Benham order yearly status reports, which is required for conservators in Tennessee.

Benham, 85, retired from the bench in 2013 and lives in Santa Barbara, Calif. In an interview, he said he didn’t know the Tuohys and wasn’t aware at the time that Oher played football. But he said he wouldn’t have been surprised to learn that Oher was an athlete.

“I’d never seen anyone that large,” Benham said. “And I wear size 14 shoes, and his shoes were a lot bigger than mine.”

Benham said he approved the conservatorship because no one opposed it. Oher and his mother, Denise, were present and signed on the dotted line. Benham said he disagreed that proving a disability or incapacity was a prerequisite under the law for a conservatorship.

He said he waived the investigator because all parties wanted the conservatorship and said the yearly status reports were the purview of the clerk, not the judge.

Chris Thomas, who was the clerk of the court at the time of the petition, said that the system of enforcement for yearly status reports in 2004 wasn’t particularly robust and that conservatorships of a person were less stringently monitored than those of an estate, where money was involved.

Benham said his “fervent hope” at the time was that the Tuohy family, with their knowledge of business, would be able to help Oher someday.

On Feb. 1, 2005, less than two months after the arrangement was granted, Oher, who had been widely recruited as a football player, committed to Mississippi. The Tuohys have said Oher made his own college decision.

Oher would eventually earn millions in the N.F.L. after he was drafted by the Baltimore Ravens in 2009. His relationship with the Tuohys also generated income through the film, books and other opportunities. Through it all, the Tuohys remained his conservators, responsible for overseeing his contracts. But the court didn’t order them to give annual updates, as the law requires, and they didn’t. For nearly 20 years after the conservatorship was granted, there were no new filings in the case.

Over the years, the Tuohys have often referred to Oher as their adopted son. And their foundation has prominently marketed that notion, using his story to promote adoptions.

In a book written in 2010 with Sally Jenkins, a Washington Post columnist, Leigh Anne Tuohy said “our adoption of Michael” was “just a formality, the legal completion of an emotional process that had started long before.”

But Oher was never actually adopted. Sean Tuohy told The Daily Memphian that lawyers had told them they couldn’t adopt someone over 18. (That wasn’t the case: Adopting an adult is legal in Tennessee.) The Tuohys said they explained the conservatorship to Oher.

Oher’s petition states that he didn’t understand until this year that he hadn’t been adopted and that the Tuohys had legal control of his affairs. His petition asks for an accounting of all the ways the Tuohys have benefited from his story and from what it calls “the lie of Michael’s adoption.”

It is clear that the success of “The Blind Side” has helped the Tuohys raise millions of dollars for themselves or their causes. According to Michael Lewis, the author of the book on which the movie was based, he and the Tuohys each made about $350,000 on the film. Oher has said he got nothing for signing away the rights to his life story.

In addition, Leigh Anne Tuohy has leveraged her fame to become a motivational speaker, charging $30,000 to $50,000 per appearance, according to available online estimates.

The Tuohys’ Making It Happen foundation, which pledges to help children who “fall through the cracks of society,” has brought in more than $1 million since 2010, including some donations from Sean Tuohy’s businesses, according to its financial disclosures. The foundation has spent less than 20 percent of its total received donations on charitable efforts, according to a Times review of records dating to 2010.

Oher’s petition alleges that Sean Tuohy amended the agreement for Oher’s life story in 2010 without his knowledge, after which the foundation received $200,000 from Alcon Entertainment, the production company for “The Blind Side.” Foundation records show a $200,000 gift from a contributor with the same address as that of Alcon. The company did not respond to requests for comment.

In recent days, the Tuohys have said they arranged the conservatorship so Oher could go to Mississippi.

“Michael was obviously living with us for a long time, and the N.C.A.A didn’t like that,” Sean Tuohy told The Daily Memphian. “They said the only way Michael could go to Ole Miss was if he was actually part of the family. I sat Michael down and told him, ‘If you’re planning to go to Ole Miss — or even considering Ole Miss — we think you have to be part of the family. This would do that, legally.’”

The Tuohys knew that a recruiting violation could have serious consequences. Indeed, just such a scenario played out at Mississippi years later. In 2017, the N.C.A.A. named more than a dozen Mississippi boosters, though not the Tuohys, and linked them to improper actions that included assisting with the recruiting of athletes and providing “impermissible benefits.” The rule violations led to a two-year postseason ban for the football team.

Athletic programs are frequently forced to break with boosters who violate recruiting guidelines. That would have been a blow to the Tuohys, who met at Mississippi and are co-chairs of its $1.5 billion fund-raising campaign.

The Tuohys also used their resources and Mississippi connections to help Oher navigate the N.C.A.A.’s academic requirements.

Oher needed to improve his grades in his senior year of high school to be eligible to play college football under N.C.A.A. rules. The Tuohys formed a team of helpers made up largely of Mississippi alumni, including another member of Leigh Anne Tuohy’s sorority.

That woman, Sue Mitchell, who was played by Kathy Bates in the film, tutored Oher extensively and was later hired by Mississippi, staying until the year Oher was drafted by the Ravens. Mitchell did not respond to multiple requests for interview.

According to Lewis’s book, the Tuohys used an idea from Ed Orgeron, the coach of Mississippi at the time, to enroll Oher in a program of 10-day courses like “Character Education.” The idea was to replace bad grades with good ones.

According to Lewis, the Tuohys realized he would be given extra time to take those classes if he were deemed to have a learning disability. Psychologists administered tests and found that Oher’s I.Q. was much higher than what similar tests had showed when he was younger. They determined that his academic struggles were the result of a learning disability because his performance wasn’t on par with the new intelligence tests, Lewis wrote.

On Aug. 1, 2005, more than eight months after the conservatorship was granted, the N.C.A.A. told Oher he was eligible to play at Mississippi.

Sean Tuohy told Lewis he wouldn’t be dissuaded from helping another person like Oher.

“So far as I can see, there’s no downside,” he said, according to Lewis’s book. “We can’t look at a kid who’s in trouble now without asking, ‘If we had him, could we turn him around?’ So what do we do when he leaves? Do we do it again?”

Susan C. Beachy contributed research.